The CVS is a version system used for developement. In this system you can check out different version of the project at will.
The CVS work with projects in what they call modules. A module could have any name, for example "mozilla".
This module contain all files to build that module. To get you hands on a CVS version you use the CVS
command to connect to the repository (in your case cvs.sourceforge .net/viewcvs.py/quickdc/), and check out
the module. Now the files are downloaded to your computer, you get your own working copy.
When you are involved in developement you check out the module, do your work and then commit
your working copy, this makes the CVS server compare your version against the one on the server and the changes are recorded.
To get a hang about CVS I recommend a quick search with google.
This seems like a page to stat with: http://www.flipcode.com/articles/article_cvsintro.shtml